CN110137982B - A method and system for dealing with three-phase unbalanced faults in grid-connected pumped-storage units - Google Patents

Abstract

The invention discloses a method and a system for dealing with a three-phase unbalanced fault of a pumped-storage unit connected to the grid. Connect the pumped-storage unit to the grid-connected system; adjust the three-phase unbalanced fault generating device to generate a three-phase unbalanced fault; when it is detected that the fault current is greater than or equal to the preset limit of the physical simulation device of the pumped-storage unit When the protection threshold is exceeded and the duration is greater than or equal to the preset duration threshold, the three-phase unbalanced fault protection is activated. The invention can simulate three-phase unbalanced faults and perform corresponding action protection, thereby improving the ability to solve the fault of the pumped-storage unit; The detection of electrical protection devices provides strong theoretical guidance and technical support.

Description

A method and system for dealing with three-phase unbalanced faults in grid-connected pumped-storage units

technical field

The present invention relates to the technical field of power system fault research, and more particularly, to a method and system for dealing with grid-connected three-phase unbalanced faults of pumped-storage units.

Background technique

Pumped-storage power station is a special power source with fast startup, fast dual-phase load tracking and fast response. It is both a power station and a power grid management tool. It has the functions of power generation, energy storage, peak regulation, frequency regulation, phase regulation, emergency backup, Black start and many other functions bring huge economic and dynamic benefits to the power system. The pumped-storage power station absorbs the abundant electric energy of the system when the load is low, and transmits power to the system when the load is peak. It cooperates with the hydropower, thermal power and nuclear power in the system, which can reduce the number of times of hydropower abandonment and thermal power unit start and stop during the flood season, and make high-efficiency thermal power generation. . The nuclear power unit runs smoothly, reducing the high fuel consumption and unit start-up and stop costs during its low-output operation, and prolonging the operating life of thermal power and nuclear power units. With the widespread application of distributed power generation and the gradual increase of large-capacity cross-regional networking projects, pumped-storage power stations that can better cope with large-scale load changes will develop more rapidly. Therefore, when conditions permit, it is necessary for the power system to build a batch of pumped storage power stations near the load center to compensate and balance the system load and ensure the economic and stable operation of the power system.

Three-phase unbalance means that the three-phase current (voltage) amplitudes in the power system are inconsistent, and the amplitude difference exceeds the specified range. The three-phase unbalance is caused by three-phase components, line parameters or load asymmetry, etc., and because the load has great uncertainty, it is very easy for the pumped storage unit connected to the power supply point to be connected to the grid. Three-phase unbalance fault occurs, which affects the safe and stable operation of the system.

The three-phase unbalanced fault will cause the instability of the motor torque, which may cause the expansion of the accident and destroy the stable operation of the system. In addition, the three-phase unbalanced fault may cause the breakdown of the motor insulation when the three-phase unbalanced fault is serious. One-phase or two-phase unbalanced faults usually occur, resulting in negative sequence currents that threaten the safety of generators.

SUMMARY OF THE INVENTION

The present invention proposes a method and system for dealing with a three-phase unbalanced fault of a pumped-storage unit connected to the grid, so as to solve the problem of how to eliminate the three-phase unbalanced fault.

In order to solve the above problems, according to an aspect of the present invention, a method for dealing with a three-phase unbalanced fault of a pumped-storage unit connected to the grid is provided, characterized in that the implementation of the method is based on a grid-connected system, and the grid-connected system Including: primary connected pumped storage unit device, three-phase unbalanced fault generating device and power system device;

The method includes:

Control the pumped-storage unit device and the power system device to meet the grid-connected conditions, and use the controller of the three-phase unbalanced fault generating device to control the three-phase synchronous switch module to close, so as to connect the pumped-storage unit to the grid-connected system ;

adjusting the three-phase unbalanced fault generating device so that the three-phase unbalanced fault occurs in the grid-connected system;

When it is detected that the fault current is greater than or equal to the preset protection threshold of the physical simulation device of the pumped-storage unit, and the duration is greater than or equal to the preset duration threshold, the three-phase unbalanced fault protection is started.

Preferably, wherein the adjusting the three-phase unbalanced fault generating device, so that the grid-connected system generates a three-phase unbalanced fault, comprising:

Use the controller to adjust the first controllable impedance of the first series sub-module or the second controllable impedance of the second series sub-module, so that a single-phase unbalanced fault occurs in the grid-connected system; or

Using the controller to adjust the first controllable impedance of the first series sub-module and the second controllable impedance of the second series sub-module, so that a two-phase unbalanced fault occurs in the grid-connected system;

Wherein, the three-phase unbalanced fault generating device includes: the controller and a three-phase synchronous switch module, and the three-phase synchronous switch module includes: a first series sub-module, a second series sub-module and a third series sub-module ; wherein, the first series sub-module further includes: a first switch connected in series with the first controllable impedance; the second series sub-module further includes: a second switch connected in series with the second controllable impedance ; The third series sub-module includes: a third switch.

Preferably, wherein said starting three-phase unbalanced fault protection includes:

Acting on the excitation adjustment device of the pumped storage unit device to achieve de-excitation; and

When the de-excitation is invalid, the failure protection of the circuit breaker at the outlet of the pumping-storage unit device is activated.

Preferably, the pumped-storage unit device includes: a pumped-storage unit including a synchronous motor, a DC generator, and excitation adjustment equipment, and a booster transformer; wherein the pumped-storage unit is connected to the booster transformer, and the excitation A regulating device is installed above the synchronous motor, and the DC generator is used to drive the synchronous motor.

Preferably, wherein the power system device comprises: a first current transformer, a second current transformer, a third current transformer, a fourth current transformer and a fifth current transformer respectively connected to a line switch, and a first current transformer A voltage transformer and a second voltage transformer; wherein, the first current transformer and the second current transformer and the third current transformer and the fourth current transformer are sequentially connected to form a series branch and are connected to the busbar where the series branch of the first current transformer and the second current transformer is connected to one end of the second voltage transformer, and the other end of the second voltage transformer is unbalanced with the three-phase The three-phase synchronous switch module of the fault device is connected; one end of the first voltage transformer is connected to one end of the step-up transformer of the pumped-storage unit device, and the other end is connected to one end of the three-phase synchronous switch module. connection; one end of the fifth current transformer is connected to the series branch formed by the third current transformer and the fourth current transformer, and the other end is connected to the power supply.

According to another aspect of the present invention, there is provided a system for dealing with three-phase unbalanced faults in grid-connected pumped-storage units. A grid-connected system, the grid-connected system includes: a pumped-storage unit device connected once, a three-phase unbalanced fault generating device, and a power system device;

The system for dealing with three-phase unbalanced faults in grid-connected pumped-storage units includes:

The system access unit is used to control the pumped-storage unit device and the power system device to meet the grid connection conditions, and use the controller of the three-phase unbalanced fault occurrence device to control the three-phase synchronous switch module to close, so as to connect the pumped-storage unit access the grid-connected system;

A fault generating unit, used for adjusting the three-phase unbalanced fault generating device, so that the three-phase unbalanced fault occurs in the grid-connected system;

The action protection unit is used to start the three-phase unbalanced fault protection when it is detected that the fault current is greater than or equal to the preset protection threshold of the physical simulation device of the pumped-storage unit, and the duration is greater than or equal to the preset duration threshold.

Preferably, wherein the fault generating unit adjusts the three-phase unbalanced fault generating device, so that the grid-connected system generates a three-phase unbalanced fault, including:

Use the controller to adjust the first controllable impedance of the first series sub-module or the second controllable impedance of the second series sub-module, so that a single-phase unbalanced fault occurs in the grid-connected system; or

Using the controller to adjust the first controllable impedance of the first series sub-module and the second controllable impedance of the second series sub-module, so that a two-phase unbalanced fault occurs in the grid-connected system;

Wherein, the three-phase unbalanced fault generating device includes: the controller and a three-phase synchronous switch module, and the three-phase synchronous switch module includes: a first series sub-module, a second series sub-module and a third series sub-module ; wherein, the first series sub-module further includes: a first switch connected in series with the first controllable impedance; the second series sub-module further includes: a second switch connected in series with the second controllable impedance ; The third series sub-module includes: a third switch.

Preferably, wherein the action protection unit, the three-phase unbalance protection module of the pumped-storage unit device starts action protection, including:

Acting on the excitation adjustment device of the pumped storage unit device to achieve de-excitation; and

When the de-excitation is invalid, the failure protection of the circuit breaker at the outlet of the pumping-storage unit device is activated.

Preferably, the pumped-storage unit device includes: a pumped-storage unit including a synchronous motor, a DC generator, and excitation adjustment equipment, and a booster transformer; wherein the pumped-storage unit is connected to the booster transformer, and the excitation A regulating device is installed above the synchronous motor, and the DC generator is used to drive the synchronous motor.

Preferably, wherein the power system device comprises: a first current transformer, a second current transformer, a third current transformer, a fourth current transformer and a fifth current transformer respectively connected to a line switch, and a first current transformer A voltage transformer and a second voltage transformer; wherein, the first current transformer and the second current transformer and the third current transformer and the fourth current transformer are sequentially connected to form a series branch and are connected to the busbar where the series branch of the first current transformer and the second current transformer is connected to one end of the second voltage transformer, and the other end of the second voltage transformer is unbalanced with the three-phase The three-phase synchronous switch module of the fault device is connected; one end of the first voltage transformer is connected to one end of the step-up transformer of the pumped-storage unit device, and the other end is connected to one end of the three-phase synchronous switch module. connection; one end of the fifth current transformer is connected to the series branch formed by the third current transformer and the fourth current transformer, and the other end is connected to the power supply.

The present invention provides a method and system for dealing with a three-phase unbalanced fault of a pumped-storage unit connected to the grid, including: controlling the pumped-storage unit device and the power system device to meet the grid-connecting conditions, and controlling the three-phase synchronous switch module to close, so as to Connect the pumped-storage unit to the grid-connected system; adjust the three-phase unbalanced fault generating device to generate a three-phase unbalanced fault; when it is detected that the fault current is greater than or equal to the preset limit of the physical simulation device of the pumped-storage unit When the protection threshold is exceeded and the duration is greater than or equal to the preset duration threshold, the three-phase unbalanced fault protection is activated. The invention can simulate the three-phase unbalanced fault that occurs in the process of power generation and grid connection of the pumped-storage power station, and can simulate the physics of single-phase unbalanced network fault and two-phase unbalanced fault of the pumped-storage unit in the laboratory, and carry out corresponding It can provide strong theoretical guidance and technical support for carrying out the test verification of the operating characteristics of the protection device of the pumped-storage unit and the detection of the relay protection device of the pumped-storage unit. It further provides a testing platform for the test of the three-phase unbalanced fault protection device of the pumped-storage unit; it can effectively avoid the damage to the operating equipment caused by the three-phase unbalanced fault of the pumped-storage unit connected to the grid, and the three-phase unbalanced fault can also be tested through simulation. The correctness of the protection action improves the safety and reliability of the pumped storage unit connected to the grid.

Description of drawings

Exemplary embodiments of the present invention may be more fully understood by reference to the following drawings:

FIG. 1 is a flowchart of a method 100 for handling a grid-connected three-phase unbalanced fault of a pumped-storage unit according to an embodiment of the present invention;

2 is a system diagram of a grid-connected system according to an embodiment of the present invention;

3 is a schematic diagram of a three-phase unbalanced fault protection according to an embodiment of the present invention; and

FIG. 4 is a schematic structural diagram of a system 400 for handling a grid-connected three-phase unbalance fault of a pumped-storage unit according to an embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for the purpose of this thorough and complete disclosure invention, and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings are not intended to limit the invention. In the figures, the same submodules/elements are given the same reference numerals.

Unless otherwise defined, terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is to be understood that terms defined in commonly used dictionaries should be construed as having meanings consistent with the context in the related art, and should not be construed as idealized or overly formal meanings.

FIG. 1 is a flowchart of a method 100 for handling a grid-connected three-phase unbalance fault of a pumped-storage unit according to an embodiment of the present invention. As shown in FIG. 1 , the method for dealing with the three-phase unbalanced fault of the pumped-storage unit connected to the grid provided by the embodiment of the present invention can simulate the three-phase unbalanced fault that occurs in the process of power generation and grid-connection of the pumped-storage power station. Simulate the physics of single unbalanced network fault and two-phase unbalanced fault of pumped-storage unit in the laboratory, and carry out corresponding action protection, which improves the ability to solve the fault of pumped-storage unit; The test verification of the operating characteristics of the device and the detection of the relay protection device of the pumped-storage unit provide strong theoretical guidance and technical support, and further provide a testing platform for the test of the three-phase unbalance fault protection device of the pumped-storage unit; it can effectively avoid the pumped storage unit. The three-phase unbalanced fault occurs when the power unit is connected to the grid, and the damage to the operating equipment can also be verified through the simulation. The method 100 for dealing with a three-phase unbalanced fault of a pumped-storage unit connected to a grid provided by an embodiment of the present invention starts from step 101, and in step 101, the pumped-storage unit device and the power system device are controlled to meet the grid-connected conditions, and the three-phase power is used The controller of the unbalance fault generating device controls the three-phase synchronous switch module to close, so as to connect the pumped-storage unit to the grid-connected system.

In step 102, the three-phase unbalanced fault generating device is adjusted so that the three-phase unbalanced fault occurs in the grid-connected system.

Preferably, wherein the adjusting the three-phase unbalanced fault generating device, so that the grid-connected system generates a three-phase unbalanced fault, comprising:

Use the controller to adjust the first controllable impedance of the first series sub-module or the second controllable impedance of the second series sub-module, so that a single-phase unbalanced fault occurs in the grid-connected system; or

Using the controller to adjust the first controllable impedance of the first series sub-module and the second controllable impedance of the second series sub-module, so that a two-phase unbalanced fault occurs in the grid-connected system;

Wherein, the three-phase unbalanced fault generating device includes: the controller and a three-phase synchronous switch module, and the three-phase synchronous switch module includes: a first series sub-module, a second series sub-module and a third series sub-module ; wherein, the first series sub-module further includes: a first switch connected in series with the first controllable impedance; the second series sub-module further includes: a second switch connected in series with the second controllable impedance ; The third series sub-module includes: a third switch.

Preferably, the pumped-storage unit device includes: a pumped-storage unit including a synchronous motor, a DC generator, and excitation adjustment equipment, and a booster transformer; wherein the pumped-storage unit is connected to the booster transformer, and the excitation A regulating device is installed above the synchronous motor, and the DC generator is used to drive the synchronous motor.

Preferably, wherein the power system device comprises: a first current transformer, a second current transformer, a third current transformer, a fourth current transformer and a fifth current transformer respectively connected to a line switch, and a first current transformer A voltage transformer and a second voltage transformer; wherein, the first current transformer and the second current transformer and the third current transformer and the fourth current transformer are sequentially connected to form a series branch and are connected to the busbar where the series branch of the first current transformer and the second current transformer is connected to one end of the second voltage transformer, and the other end of the second voltage transformer is unbalanced with the three-phase The three-phase synchronous switch module of the fault device is connected; one end of the first voltage transformer is connected to one end of the step-up transformer of the pumped-storage unit device, and the other end is connected to one end of the three-phase synchronous switch module. connection; one end of the fifth current transformer is connected to the series branch formed by the third current transformer and the fourth current transformer, and the other end is connected to the power supply.

FIG. 2 is a system diagram of a grid-connected system according to an embodiment of the present invention. As shown in FIG. 2, in the embodiment of the present invention, the grid-connected system includes: a three-phase unbalanced fault simulation device, an equivalent pumped-storage unit physical simulation device, and an equivalent power system physical simulation device. One end of the balance fault simulation device is connected to the equivalent pumped storage unit physical simulation device, and the other end is connected to the equivalent power system physical simulation device. When the grid-connected conditions are met, the controller controls the three-phase synchronous switch to close, and the pumped-storage unit is connected to the system for operation.

Wherein, the three-phase unbalanced fault simulation device includes: a controller and a three-phase synchronous switch module; the three-phase synchronous switch module includes: a first series sub-module, a second series sub-module and a third series sub-module; wherein , the first series sub-module further includes: a first controllable impedance Z1 and a first switch K1; the second series sub-module includes: a second controllable impedance Z2 and a second switch K2; the third series sub-module The module includes: a third switch K3. The controller of the three-phase unbalanced fault simulation device can adjust the resistance value of the controllable impedance, and the adjustment range of the controllable impedance is 0-200Ω. By adjusting the organization of the controllable impedance, the magnitude of the unbalanced fault phase current of the module can be correspondingly. Among them, the resistance value of the controllable impedance can be adjusted by the manual knob, or remotely controlled by the controller, and adjusted by inputting the corresponding value in the controller.

When simulating a three-phase unbalanced fault, adjusting the controllable impedance Z1 or Z2 can simulate a single-phase unbalanced fault, while adjusting the controllable impedance Z1 and Z2 can simulate a two-phase unbalanced fault. The magnitude of the corresponding unbalanced fault phase current can be simulated.

The equivalent power system physical simulation device is used for simulating a real power system, providing grid connection conditions for the equivalent pumped storage unit physical simulation unit to simulate the pumped storage unit, and the equivalent pumped storage unit physical simulation device is used to simulate Grid-connected pumped storage units.

The physical simulation device of the equivalent pumped-storage unit includes: a synchronous motor/generator, a water pump/turbine (DC generator/motor), a step-up transformer and an excitation adjustment device; wherein the pumped-storage unit is connected to the step-up transformer, and the excitation device Mounted above the synchronous motor/generator. Among them, the DC generator/motor simulates the pump/turbine, the DC generator state with resistance load simulates the pump pumping load, and the DC motor running state simulates the turbine to drive the synchronous generator to generate electricity. Wherein, the excitation regulator is an excitation regulator.

The equivalent power system physical simulation device includes current transformers CT1 to CT5 and voltage transformers PT1 and PT2. The current transformers CT1 and CT2, CT3 and CT4 are sequentially connected to form a series branch and are connected to the busbar, wherein the CT1-CT2 series branch is connected to the synchronous switch, and one end of the voltage transformer PT1 is physically connected to the equivalent pumped storage unit. One end of the booster transformer of the analog device is connected, the other end is connected to one end of the three-phase synchronous switch module, one end of the voltage transformer PT2 is connected to one end of the three-phase synchronous switch module, and the other end is connected to the CT1-CT2 series branch. The current transformer CT5 is connected to the power supply, and the current transformers CT1 to CT5 are all connected to a line switch.

In the embodiment of the present invention, when a single-phase unbalanced fault occurs when the simulated pumped-storage unit is connected to the grid, the impedance value of the controllable impedance value Z1 is kept as 0, and the impedance value of the controllable impedance Z2 is adjusted to simulate the corresponding single-phase Unbalanced fault; or keep the impedance value of the controllable impedance Z2 at 0, and adjust the impedance value of the controllable impedance value Z1 to simulate the corresponding single-phase unbalanced fault.

When the two-phase unbalanced fault occurs when the simulated pumped-storage unit is connected to the grid, the impedance values of the controllable impedance values Z1 and Z2 are adjusted at the same time to simulate the corresponding two-phase unbalanced fault.

In step 103, when it is detected that the fault current is greater than or equal to the preset protection threshold of the physical simulation device of the pumped-storage unit, and the duration is greater than or equal to the preset duration threshold, the three-phase unbalanced fault protection is activated.

Preferably, wherein said starting three-phase unbalanced fault protection includes:

Acting on the excitation adjustment device of the pumped storage unit device to achieve de-excitation; and

When the de-excitation is invalid, the failure protection of the circuit breaker at the outlet of the pumping-storage unit device is activated.

FIG. 3 is a schematic diagram of three-phase unbalanced fault protection according to an embodiment of the present invention. As shown in Figure 3, I _2fqx is the preset protection threshold of the negative-sequence current element; I _0fqx is the protection threshold of the zero-sequence current element; T _sl is the preset duration threshold of the three-phase unbalanced protection; J _ka , J _kb and J _kc are the normally closed auxiliary nodes of A, B, and C phases of the three-phase synchronous switch in Figure 2, respectively; when the detected negative sequence current is greater than I _2fqx , the zero sequence current is greater than I _0fqx , and continues When the time is greater than T _sl , the action protection is activated.

Specifically, when it is detected that the negative sequence current corresponding to the current of the single-phase unbalanced fault reaches the preset protection threshold of the physical simulation device of the pumped-storage unit, the three-phase unbalanced fault protection for the grid-connected pumped-storage unit is activated, and the action De-excitation of the excitation device of the pumped-storage unit; when the de-excitation is invalid, the failure protection of the outlet circuit breaker of the pumped-storage unit is activated.

When the negative sequence current corresponding to the detected two-phase unbalanced fault current reaches the preset protection threshold of the pumped-storage unit physical simulation device, the pumped-storage unit is connected to the grid and three-phase unbalanced fault protection occurs, and the pumped-storage unit is activated. The excitation device of the unit is de-excited; when the de-excitation is invalid, the failure protection of the outlet circuit breaker of the pumped storage unit is activated.

FIG. 4 is a schematic structural diagram of a system 400 for handling a grid-connected three-phase unbalance fault of a pumped-storage unit according to an embodiment of the present invention. As shown in FIG. 4 , the implementation of the system 400 for dealing with the three-phase unbalance fault of the grid-connected pumped-storage unit in the same embodiment of the present invention is based on the grid-connected system, and the grid-connected system includes: a pumped-storage unit device connected at one time , a three-phase unbalanced fault generating device and a power system device; the system 400 for dealing with a three-phase unbalanced fault of a pumped-storage unit connected to the grid includes: a system access unit 401 , a fault generating unit 402 and an action protection unit 403 .

Preferably, the system access unit 401 is used to control the pumped-storage unit device and the power system device to meet the grid connection conditions, and use the controller of the three-phase unbalanced fault generating device to control the three-phase synchronous switch module to close, so as to connect the The pumped-storage unit is connected to the grid-connected system.

Preferably, the pumped-storage unit device includes: a pumped-storage unit including a synchronous motor, a DC generator, and excitation adjustment equipment, and a booster transformer; wherein the pumped-storage unit is connected to the booster transformer, and the excitation A regulating device is installed above the synchronous motor, and the DC generator is used to drive the synchronous motor.

Preferably, wherein the power system device comprises: a first current transformer, a second current transformer, a third current transformer, a fourth current transformer and a fifth current transformer respectively connected to a line switch, and a first current transformer A voltage transformer and a second voltage transformer; wherein, the first current transformer and the second current transformer and the third current transformer and the fourth current transformer are sequentially connected to form a series branch and are connected to the busbar where the series branch of the first current transformer and the second current transformer is connected to one end of the second voltage transformer, and the other end of the second voltage transformer is unbalanced with the three-phase The three-phase synchronous switch module of the fault device is connected; one end of the first voltage transformer is connected to one end of the step-up transformer of the pumped-storage unit device, and the other end is connected to one end of the three-phase synchronous switch module. connection; one end of the fifth current transformer is connected to the series branch formed by the third current transformer and the fourth current transformer, and the other end is connected to the power supply.

Preferably, the fault occurrence unit is 402 yuan, which is used to adjust the three-phase unbalanced fault generating device, so that the three-phase unbalanced fault occurs in the grid-connected system.

Preferably, wherein the fault generating unit 402 adjusts the three-phase unbalanced fault generating device, so that the grid-connected system generates a three-phase unbalanced fault, comprising: adjusting the first series of sub-modules by using the controller controllable impedance or the second controllable impedance of the second series sub-module, so that a single-phase unbalanced fault occurs in the grid-connected system; or using a controller to adjust the first controllable impedance of the first series sub-module and the second series connection A second controllable impedance of the sub-modules, so that a two-phase unbalanced fault occurs in the grid-connected system.

Wherein, the three-phase unbalanced fault generating device includes: the controller and a three-phase synchronous switch module, and the three-phase synchronous switch module includes: a first series sub-module, a second series sub-module and a third series sub-module ; wherein, the first series sub-module further includes: a first switch connected in series with the first controllable impedance; the second series sub-module further includes: a second switch connected in series with the second controllable impedance ; The third series sub-module includes: a third switch.

Preferably, the action protection unit 403 is configured to start the three-phase fault when it is detected that the fault current is greater than or equal to the protection threshold of the physical simulation device of the pumped-storage unit, and the duration is greater than or equal to the preset duration threshold. Balanced fault protection.

Preferably, in the action protection unit 403, the three-phase unbalance protection module of the pumped-storage unit device starts the action protection, including: operating the excitation adjustment device of the pumped-storage unit device to realize de-excitation; and when After the demagnetization is invalid, the failure protection of the circuit breaker at the outlet of the pumping-storage unit device is activated.

The system 400 for handling a three-phase unbalance fault in a grid-connected pumped-storage unit according to an embodiment of the present invention corresponds to a method 100 for handling a grid-connected three-phase unbalance fault in a pumped-storage unit according to another embodiment of the present invention. No longer.

The present invention has been described with reference to a few embodiments. However, as is known to those skilled in the art, other embodiments than the above disclosed invention are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/the/the [means, component, etc.]" are open to interpretation as at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (4)

1. The method for processing the grid-connected three-phase imbalance fault of the pumped storage unit is characterized in that the method is realized based on a grid-connected system, and the grid-connected system comprises the following steps: the system comprises a pumped storage unit device, a three-phase unbalance fault generating device and a power system device which are connected at one time;

the method comprises the following steps:

controlling a pumped storage unit device and an electric power system device to meet grid-connected conditions, and controlling a three-phase synchronous switch module to be closed by using a controller of a three-phase unbalance fault generating device so as to connect the pumped storage unit into the grid-connected system;

adjusting a three-phase unbalance fault generating device to enable the grid-connected system to generate a three-phase unbalance fault;

when the fault current is detected to be greater than or equal to a preset protection threshold value of the physical simulation device of the pumped storage unit, and the duration time is detected to be greater than or equal to a preset duration time threshold value, starting three-phase unbalanced fault protection;

wherein the initiating three-phase imbalance fault protection comprises:

the excitation adjusting equipment acts on the pumped storage unit device to realize demagnetization; and

when the de-excitation is invalid, starting the failure protection of the circuit breaker at the outlet of the pumped storage unit device;

wherein, adjust unbalanced three phase trouble generating device to make the grid-connected system produce unbalanced three phase trouble, include:

adjusting a first controllable impedance of a first series submodule or a second controllable impedance of a second series submodule by using the controller so as to enable the grid-connected system to generate a single-phase unbalance fault; or

Adjusting a first controllable impedance of a first series submodule and a second controllable impedance of a second series submodule by using a controller so as to enable the grid-connected system to generate a two-phase unbalance fault;

wherein, the unbalanced three phase fault generating apparatus includes: the controller and three-phase synchronous switch module, three-phase synchronous switch module includes: a first, second, and third concatenation sub-modules; wherein the first concatenation sub-module further comprises: a first switch in series with the first controllable impedance; the second series submodule further includes: a second switch in series with the second controllable impedance; the third series submodule includes: a third switch;

wherein the power system device includes: the first current transformer, the second current transformer, the third current transformer, the fourth current transformer and the fifth current transformer, as well as the first voltage transformer and the second voltage transformer are respectively connected with a line switch; the first current transformer, the second current transformer, the third current transformer and the fourth current transformer are sequentially connected to form a series branch and are connected to a bus; the series branch of the first current transformer and the second current transformer is connected with one end of a second voltage transformer, and the other end of the second voltage transformer is connected with a three-phase synchronous switch module of the three-phase unbalanced fault device; one end of the first voltage transformer is connected with one end of a boosting transformer of the pumped storage unit device, and the other end of the first voltage transformer is connected with one end of the three-phase synchronous switch module; one end of the fifth current transformer is connected with a series branch formed by the third current transformer and the fourth current transformer, and the other end of the fifth current transformer is connected into a power supply.

2. The method of claim 1, wherein the pumped-storage-unit-means comprises: the system comprises a pumped storage unit and a step-up transformer, wherein the pumped storage unit comprises a synchronous motor, a direct current generator and excitation adjusting equipment; the pumped storage unit is connected with the booster transformer, the excitation adjusting equipment is installed above the synchronous motor, and the direct-current generator is used for driving the synchronous motor.

3. The utility model provides a system for handle pumped storage group unbalanced three phase that is incorporated into power networks trouble, its characterized in that, the realization of system for handling pumped storage group unbalanced three phase that is incorporated into power networks trouble is based on the system that is incorporated into power networks, the system that is incorporated into power networks includes: the system comprises a pumped storage unit device, a three-phase unbalance fault generating device and a power system device which are connected at one time;

the system for processing the grid-connected three-phase imbalance fault of the pumped storage unit comprises:

the system access unit is used for controlling the pumped storage unit device and the power system device to meet grid-connected conditions, and controlling the three-phase synchronous switch module to be closed by using a controller of the three-phase unbalanced fault generating device so as to access the pumped storage unit into the grid-connected system;

the fault generating unit is used for adjusting the three-phase unbalanced fault generating device so as to enable the grid-connected system to generate a three-phase unbalanced fault;

the action protection unit is used for starting three-phase unbalanced fault protection when the fault current is detected to be greater than or equal to a preset protection threshold value of the physical simulation device of the pumped storage unit and the duration time is detected to be greater than or equal to a preset duration time threshold value;

wherein, action protection unit, the unbalanced three phase protection module start-up action protection of pumped storage unit device includes:

the excitation adjusting equipment acts on the pumped storage unit device to realize demagnetization; and

when the de-excitation is invalid, starting the failure protection of the circuit breaker at the outlet of the pumped storage unit device;

wherein, the fault generating unit adjusts the unbalanced three-phase fault generating device to make the grid-connected system generate unbalanced three-phase fault, including:

adjusting a first controllable impedance of a first series submodule or a second controllable impedance of a second series submodule by using the controller so as to enable the grid-connected system to generate a single-phase imbalance fault; or

Adjusting a first controllable impedance of a first series submodule and a second controllable impedance of a second series submodule by using a controller so as to enable the grid-connected system to generate a two-phase unbalance fault;

wherein, the unbalanced three phase fault generating apparatus includes: the controller and three-phase synchronous switch module, three-phase synchronous switch module includes: a first, second, and third concatenation submodules; wherein the first concatenation sub-module further comprises: a first switch in series with the first controllable impedance; the second series submodule further comprises: a second switch in series with the second controllable impedance; the third series submodule includes: a third switch;

wherein the power system device includes: the first current transformer, the second current transformer, the third current transformer, the fourth current transformer and the fifth current transformer, as well as the first voltage transformer and the second voltage transformer are respectively connected with a line switch; the first current transformer, the second current transformer, the third current transformer and the fourth current transformer are sequentially connected to form a series branch and are connected to a bus; the series branch of the first current transformer and the second current transformer is connected with one end of a second voltage transformer, and the other end of the second voltage transformer is connected with a three-phase synchronous switch module of the three-phase unbalanced fault device; one end of the first voltage transformer is connected with one end of a boosting transformer of the pumped storage unit device, and the other end of the first voltage transformer is connected with one end of the three-phase synchronous switch module; one end of the fifth current transformer is connected with a series branch formed by the third current transformer and the fourth current transformer, and the other end of the fifth current transformer is connected into a power supply.

4. The system of claim 3, wherein the pumped-storage-group-means comprises: the system comprises a water pumping energy storage unit and a boosting transformer, wherein the water pumping energy storage unit comprises a synchronous motor, a direct-current generator and excitation adjusting equipment; the water-pumping energy storage unit is connected with the booster transformer, the excitation adjusting equipment is installed above the synchronous motor, and the direct-current generator is used for driving the synchronous motor.

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